Contrasting interannual changes in phytoplankton productivity and community structure in the coastal Canadian Arctic Ocean

• Published in: Limnology and Oceanography
• Main Authors: Blais, Marjolaine, Ardyna, Mathieu, Gosselin, Michel, Dumont, Dany, Bélanger, Simon, Tremblay, Jean-Éric, Gratton, Yves, Marchese, Christian, Poulin, Michel
• Other Authors: Institut des Sciences de la MER de Rimouski (ISMER), Université du Québec à Rimouski (UQAR), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Division of Vaccine Discovery, La Jolla Institute for Immunology La Jolla, CA, États-Unis, Department of Biology Québec, Université Laval Québec (ULaval), Centre Eau Terre Environnement Québec (INRS - ETE), Institut National de la Recherche Scientifique Québec (INRS), Centre de Géosciences (GEOSCIENCES), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Arctic; Arctic Ocean; Baffin Bay; Baffin; Beaufort Sea; Climate change; Phytoplankton; Sea ice
• Online Access: https://hal.archives-ouvertes.fr/hal-03502947; https://doi.org/10.1002/lno.10581

The rapid physical changes affecting the Arctic Ocean alter the growth conditions of primary producers. In this context, a crucial question is whether these changes will affect the composition of phytoplankton communities, augment their productivity, and eventually enhance food webs. We combined satellite and model products with in situ datasets collected during fall and provide new insights into the response of phytoplankton biomass and production in the Canadian Arctic by comparing an interior shelf (Beaufort Sea) and an outflow shelf (Baffin Bay). Correlation analysis was used to distinguish between seasonal and interannual variability and revealed that most biological variables are responding to the interannual pressures of climate change. In southeast Beaufort Sea, a change in phytoplankton community composition occurred, with a significant increase in diatoms from 2% (2002) to 37% (2010-2011) of the total protist abundance. In 2011, photosynthetic picoeukaryotes were twice as abundant as in 2002. For these two phytoplankton groups, abundance was correlated with the duration of the open-water period, which also increased and affected vertical stratification and sea-surface temperature. In contrast, there was a sharp decline in centric diatom abundance as well as in phytoplankton biomass and production in northern Baffin Bay over the years considered. These decreases were linked to changes in seasonal progression and sea-ice dynamics through their impacts on vertical stratification and freshwater input. Overall, our results highlight the importance of stratification and the duration of the open-water period in shaping phytoplankton regimeseither oligotrophic or eutrophicin marine waters of the Canadian Arctic.